Diagnostic instrument



FIG. 1 is a front perspective view of a Diagnostic Instrument;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a side view thereof; and,

FIG. 5 is another side view thereof.

The broken lines in FIGS. 1, 2, 4, and 5 are included for the purpose of illustrating portions of the diagnostic instrument that form no part of the claimed design. 

The ornamental design for a diagnostic instrument, as shown and described. 